"Examining examples and non-examples can help students understand definitions.... Is the provision of examples always desirable? Would it perhaps be better to ask undergraduate students to provide their own examples and non-examples? Would they be able to? Given a false conjecture, would students be able to come up with counterexamples? Several studies shed light on these questions." Organized into four sections: Successful Math Majors Generate Their Own Examples; Being Asked for Examples Can Be Disconcerting; Generating Counterexamples that Are Explanatory; and "If I Don't Know What It Says, How Can I Find an Example of It?" From the MAA's Teaching and Learning Research Sampler.